help with compound payments

Sue0113

Junior Member
Joined
Feb 1, 2012
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114
could someone help e find the formula?

you lend a friend $800 anf they agree to make quarterly payments for 1 year. You charge your friend 8.52% compounded quarterly. What is the size of payments?
 
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help finding the formula

have not worked with annuity....only Present value
I thought formula was PV=FV(1+i)^-4
800((1+.0213)^4
800(1.087961)
870.37
870.37 devided by 4
so four equal payments of 217.59
 
Is this the formula and work?

Is this problem worked out correctly now?
 
reworked problem

800=PMT[1-(1.0852)^-.25]
----------------
.0852
800=PMT[1-(1.889154807)
800=PMTx.889154807
PMT=800/.889154807
PMT=899.7308384
899.73/4=224.93
PMT=224.93

So in order to pay the friend back he would have to make 4 payments of 224.93. Is this correct?
 
Hello, Sue0113!

If you're careful, you can "walk" your way through this one.
But wear your hiking boots, it's a long walk.

You lend a friend $800 and they agree to make quarterly payments for one year.
You charge your friend 8.52% compounded quarterly. .What is the size of payments?

Let \(\displaystyle P\) = the principal, $800.
Let \(\displaystyle i\) = the interest rate, \(\displaystyle \frac{0.0852}{4} = 0.0213\)
Let \(\displaystyle X\) = the quarterly payment

Note: If he owes \(\displaystyle D\) dollars at the beginning of a quarter,
. . . . at the end of the quarter, he will owe: \(\displaystyle D + Di \,=\,D(1+i)\) dollars.


At the beginning of the year, he owes you \(\displaystyle P\) dollars.


End of 1st quarter:

With interest, he owes: .\(\displaystyle P(1+i)\) dollars.
He repays \(\displaystyle X\) dollars.
His balance is: .\(\displaystyle P(1+i) - X\) dollars.


End of 2nd quarter:

With interest, he owes:. \(\displaystyle \big[P(1+i) - X\big](1+i)\)
. . \(\displaystyle =\:p(1+i)^2 -X(1+i)\) dollars.
He repays \(\displaystyle X\) dollars.
His balance is: .\(\displaystyle P(1+i)^2 - X(1+i) - X\) dollars.


End of 3rd quarter:

With interest, he owes: .\(\displaystyle \big[P(1+i)^2 - X(1+i) - X\big](1+i)\)
. . \(\displaystyle =\:p(1+i)^3 - X(1+i)^2 - X(1+i)\) dollars.
He repays \(\displaystyle X\) dollars.
His balance is: .\(\displaystyle P(1+i)^3 - X(1+i)^2 - X(1+i) - X\) dollars.


End of 4th quarter:

With interest, he owes: .\(\displaystyle \big[P(1+i)^3 - X(1+i)^2 - X(1+i) - X\big](1+i)\)
. . \(\displaystyle -\:p(1+i)^4 - X(1+i)^3 - X(1+i)^2 - X(1+i)\) dollars.
He repays \(\displaystyle X\) dollars.
His balance is: .\(\displaystyle P(1+i)^4 - X(1+i)^3 - X(1+i)^2 - X(1+i) - X\) dollars.


But at this time, he has completey repaid the loan; his balance is zero.

. . \(\displaystyle P(1+i)^4 - X(1+i)^3 - X(1+i)^2 - X(1+i) - X \;=\;0\)

. . \(\displaystyle P(1 + i)^4 \;=\;X(1+i)^3 + X(1+i)^2 + X(1+i) + X\)

. . \(\displaystyle P(1+i)^4 \;=\;X\big[(1+i)^3 + (1+i)^2 + (1+i) + 1\big]\)

. . \(\displaystyle P(1+i)^4 \;=\;X\,\dfrac{(1+i)^4-1}{(1+i) - 1}\)

. . \(\displaystyle P(1+i)^4 \;=\;X\,\dfrac{(1+i)^4-1}{i}\)

\(\displaystyle \text{Therefore: }\;X \;=\;P\,\dfrac{i(1+i)^4}{(1+i)^4-1} \)


We have: .\(\displaystyle P = 800,\;i = 0.0213\)

\(\displaystyle \text{Therefore: }\:X \;=\;800\,\dfrac{(0.0213)(1.0213)^4}{(1.0213^4-1} \;=\; 210.7622178\)

His payments are $210.76 per quarter.
 
We have not learnt Annuity

Denis we are not into annuity as of yet however we may get into it.
after reading both the explainations I now have a further understand but Soroban explained it as we are learning
FV=x+E4+E3+E2+E1
So your both right and you both helped me understand.
 
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